A compressor applied to a plant apparatus or the like is driven by a driving source such as a steam turbine. A rotary shaft of the steam turbine as a driving shaft and a rotary shaft of the compressor as a driven shaft are connected to each other via a coupling such as a flange-shaped flexible shaft joint so that torque of the steam turbine is transmitted (refer to, for example, PTL 1). Even in a case where the center lines of both shafts are unlikely to perfectly correspond to each other, a structure that allows the mismatch is available because of the use of the flange-shaped flexible shaft joint.
In general, a bearing device that performs lubrication by oil bath lubrication (forced lubrication) is used as a bearing device which is disposed in an end portion of a rotary shaft in, for example, a large rotary machine such as a uniaxial multistage centrifugal compressor.